Field of the Invention
The present teaching relates to a piezoelectric actuator and a method for manufacturing the piezoelectric actuator.
Description of the Related Art
Japanese Patent Application Laid-open No. 2013-111819 discloses a piezoelectric actuator which is provided to discharge the ink from nozzles of a recording head based on the ink-jet system. The piezoelectric actuator is arranged on a flow passage forming substrate composed of silicon which is formed with a plurality of pressure chambers. Note that the plurality of pressure chambers are communicated respectively with the plurality of nozzles of a nozzle plate joined to the flow passage forming substrate.
The piezoelectric actuator is provided with a plurality of piezoelectric elements which correspond to the plurality of pressure chambers respectively. The plurality of piezoelectric elements is arranged opposingly to the plurality of pressure chambers respectively on an elastic film of the flow passage forming substrate which covers the plurality of pressure chambers. Each of the piezoelectric elements has a lower electrode film, a piezoelectric body, and an upper electrode film which are stacked in this order from the side of the flow passage forming substrate. The lower electrode film is an individual electrode which is provided individually for each of the piezoelectric bodies. A wiring (lead electrode) is connected to a portion of the lower electrode film which is exposed while protruding from the piezoelectric body. On the other hand, the upper electrode films are in conduction with each other among the plurality of piezoelectric elements, and the upper electrode film functions as a common electrode. When a voltage is applied between the lower electrode film and the upper electrode film in each of the piezoelectric elements, then the deformation occurs in the piezoelectric body, and thus the pressure of the ink contained in the pressure chamber is raised. Accordingly, the ink is discharged from the nozzle which is communicated with the pressure chamber.
The piezoelectric actuator described above is manufactured by performing the following steps. At first, an electrode film is formed as a film on the elastic film of the flow passage forming substrate, for example, by means of the sputtering method. The patterning is performed for the electrode film to form the plurality of lower electrode films. Subsequently, a piezoelectric material film is formed as a film on the substantially entire surface of the elastic film formed with the plurality of lower electrode films. After that, the piezoelectric material film is subjected to the patterning to form the plurality of piezoelectric bodies which cover the plurality of lower electrode films respectively. Subsequently, an electrode film is formed as a film to cover the plurality of piezoelectric bodies, and then the electrode film is subjected to the patterning to form the upper electrode film.